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A step down transformer works on 220 vol...

A step down transformer works on 220 volts a.c. mains. It is used to light at 100W, 20V bulb. The main current is 0.5A. What is the efficiency of the transformer?

A

0.91

B

0.8

C

0.71

D

0.51

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CHETANA PUBLICATION-Electromagnetic Induction-EXERCISE
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  8. A transformer is used to reduce the mains supplyof 220V to 22V.If the ...

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  9. The core of a transformer is laminated

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  10. A step down transformer of efficiency 80% is used on a 1000V line to d...

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  11. Henry is equivalent to

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  12. The primary winding of transformer has 200 turns and its secondary win...

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  13. A transformer is used to reduce the main supply of 220 V to11 V. If th...

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  17. If south pole of the magnet is moved towards the coil then the nearer ...

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  18. The current in the choke coil decreasing at the rate of 3 A//s and cho...

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